This article was co-authored by Chris M. Matsko, MD. Dr. Matsko is a retired Physician in Pennsylvania. He received his M.D. from the Temple University School of Medicine in 2007.

There are 21 references cited in this article, which can be found at the bottom of the page.

Patch testing your skin can mean two different things. In the first instance, your doctor may patch test your skin for certain allergens. In the second instance, you may want to patch test a new product you've bought to see if you can use it on your skin. Both are testing for allergic reactions to an irritant.

Steps

Method1

Having Your Skin Allergy Tested

1

Understand the basics. Patch tests are used to test how allergic you are when you come into contact with certain substances. Patch tests are different from prick or scratch tests.[1]

A scratch test checks for reactions to common allergens that may give you symptoms from hives to a runny nose. The nurse scratches or pricks the skin to get the allergen under the skin.[2]

A patch test checks for just the skin's reaction to the allergen. A reaction to an allergen by the skin is known as contact dermatitis.[3]

2

Discuss your medications with your doctor. Certain medications can affect a patch test. Antihistamines, for instance, are designed to suppress allergic reactions, which can change the outcome of your patch test. Your doctor may want you to go off of these medications for a bit before your test, up to 10 days ahead of time.[4]

Other medications that may cause problems include tricyclic antidepressants, some medications for acid reflux (such as ranitidine), and omalizumab (an asthma medication).[5]

3

Be ready for what will happen. During a patch test, the nurse or doctor will make up a series of small patches. Each patch will contain a small amount of a different substance that has been known to cause reactions in some people. For instance, some patch tests use everything from metals such as cobalt and nickel to lanolin and certain plant types. The patches will be attached to your skin with medical tape. Most of the time, the patches are applied to your back or arm.[6]

4

Ask about photo-patch testing. If you commonly have rashes on the back of your hands, your neck, or arms, you may react to a substance only when it comes into contact with sunlight. A special test exists for this purpose; if you need a photo-patch test, your doctor will place two of each substance and expose one of them to light, while not exposing the other.[7]

5

Don't be afraid if you think it will be painful. In fact, unlike scratch tests, patch tests don't use needles at all. Therefore, you won't experience any pain when the patches are being applied.[8]

6

Keep the area dry. While the patches are on, you should avoid getting the patches wet, which means avoiding extremes of heat and humidity and heavy sweating. Do not swim, shower, take a bath, exercise or do anything that might cause the patch to get wet.[9]

7

Wait two days. Generally, the patches are left on you for two days. You return to the doctor after the time period is up. The nurse or doctor will remove your patches and look at your skin. One of them will see which substances your skin shows a reaction to.[10]

Reactions on your skin may appear as a rash, possibly with small, raised areas that resemble pimples or fluid-filled sacs.

8

Wait another two days. Sometimes, the doctor will have you return again, four days after the original test. This step is to see if you had a delayed reaction to an allergen.[11]

9

Avoid the irritants. Once you know what causes you trouble, you know what to avoid. Your doctor can give you advice on avoiding your particular irritant. On the other hand, if you don't react to anything, your doctor will look to other issues as the cause of any rashes you may have.[12]

Method2

Testing New Products on Your Skin

1

Understand product skin testing. When you get a new product, such as a chemical peel or even just a facial cleanser, it's important to patch test it first, especially if you have sensitive skin. Patch testing just means you use a small amount on part of your skin to see how you react.[13]

In other words, you don't want to rub something all over your face or body and break out in hives everywhere. It's best to limit the area at first.[14]

You should also skin test other products, such as shampoos, conditioner, and hair dyes. Basically, if you have sensitive skin, you should skin test any product that comes in contact with your skin.

2

Put a small amount on your inner arm. Your inner arm is a good place to test because generally that skin is fairly sensitive. In addition, it won't be too noticeable if you do have a reaction.[15]

If the product burns or causes an immediate reaction, wash it off as quickly as possible.[16]

3

Wait for 24 hours. If it's a product such as lotion, leave it on your skin.[17] If it's a product like a chemical peel that's meant to be rinsed off, rinse it off at the appropriate time.[18] Wait a full day to see if you have a reaction to the product.

A reaction could be your skin turning red, welting up, or showing a rash. You could also have scaliness or oozing skin. Another symptom is itchiness.[19]

4

Test a more sensitive area. Next, move to skin testing a more sensitive area. This time, pick a place where the product will be used. For instance, if you are using a facial cleanser, try it just under your ear in a small spot. The reason you need to test it again is because it may affect a more sensitive area of skin even if it doesn't affect your arm.[20]

5

Wait another day. Once again, wait for a full day to see if your skin reacts to the product. If it doesn't, you should be fine to use it.[21]

What should I do for a chemical mask that says to leave it on for only 10 minutes? Do I leave it for the 10 minutes and then rinse the area?

Community Answer

If the instructions say you should leave it on for 10 minutes, then you should leave it on for 10 minutes, and once you're done, rinse it off with water. If the bottle has any other instructions, be sure to read them carefully and follow them.

If you have a new product and want to do a patch skin test, place a small amount on your inner arm because it won’t be too noticeable if you have a reaction. Some products may start to burn your skin or react immediately. If so, wash them off right away to reduce as much damage to your skin as possible. Once you have the product on your arm, leave it on for a full 24 hours to see if it makes your skin turn red, start to rash, or become itchy. If it doesn’t, you can try the product on a more sensitive area, like just behind the ear, for another 24 hours to see if it has any effect. If not, the product should be fine to use. For more advice from our Medical co-author, like how to have your skin allergy tested with a patch skin test, scroll down!

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Article Info

This article was co-authored by Chris M. Matsko, MD. Dr. Matsko is a retired Physician in Pennsylvania. He received his M.D. from the Temple University School of Medicine in 2007.